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Topic: Compressive stress

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In the News (Thu 25 Apr 19)

  Arc tube with residual-compressive-stress layer for discharge lamp unit and method of manufacturing same - Patent ...
As a result, the inventor discovered that retention of compressive stress produced in the pinch seal portions 5b during the arc tube manufacturing process causes a thermal stress in the glass layer in the pinch seal portion to disperse due to rise in the temperature occurring after turning the arc tube on.
The compressive stress layer is previously formed in a predetermined wide region in the axial direction or/and the circumferential direction on the surface of hermetic contact between the glass layer and the electrode rod.
Therefore, the compressive stress layer (the residual compressive stress layer) formed in the large range efficiently relaxes (absorbs) the thermal stress produced in the glass layer as the temperature is raised.
www.freepatentsonline.com /6452334.html   (5448 words)

  Shear stress - Wikipedia, the free encyclopedia   (Site not responding. Last check: 2007-10-29)
Shear stress is a stress state where the shape of a material tends to change (usually by "sliding" forces - torque by transversely-acting forces) without particular volume change.
Structural members in pure shear stress are the torsion bars and the driveshafts in automobiles.
Cantilevers, beams, consoles and column heads are subject to composite loading, consisting of shear, tensile and compressive stress.
www.sterlingheights.us /project/wikipedia/index.php/Shear_stress   (327 words)

 Strength of materials
Compressive stress (or compression) is the stress state when the material tends to compact (volume decrease).
Shear stress is caused when a force is applied to produce a sliding failure of a material along a plane that is parallel to the direction of the applied force e.g.
Compressive strength is a limit state of compressive stress that leads to compressive failure in the manner of ductile failure (infinite theoretically yield) or in the manner of brittle failure (rupture as the result of crack propagation, or sliding among a weak plane - see Shear strength).
www.brainyencyclopedia.com /encyclopedia/s/st/strength_of_materials.html   (762 words)

 Compressive stress -- Facts, Info, and Encyclopedia article   (Site not responding. Last check: 2007-10-29)
Compressive stress is the (The relative prominence of a syllable or musical note (especially with regard to stress or pitch)) stress applied to materials resulting in their compaction (decrease of volume).
Usually compressive stress applied to bars, ((architeture) a tall cylindrical vertical upright and used to support a structure) columns, etc. leads to shortening.
Compressive stress has (The relative prominence of a syllable or musical note (especially with regard to stress or pitch)) stress units (force per area), usually with (A reply of denial) negative values to indicate the compaction.
www.absoluteastronomy.com /encyclopedia/c/co/compressive_stress.htm   (342 words)

 Stress Relief Basics - September 2001
The residual stress decreases to that of the lower yield strength, and it is thereby relieved.
For carbon and low-alloy steels, stress relieving is commonly performed in the range of 1100° to 1350°F. The time at which the weldment is held at temperature is dependent on the thickness of the workpiece and its chemical composition.
The tensile residual stresses at the surface of the weldment must "overcome" the compressive stress for a fatigue crack to initiate.
www.aws.org /wj/sept01/cullison.html   (796 words)

 Sputtered spring films with low stress anisotropy - US Patent 6866255   (Site not responding. Last check: 2007-10-29)
In one embodiment, isotropic internal stress is achieved by manipulating the fabrication parameters (i.e., temperature, pressure, and electrical bias) during spring material film information to generate the tensile or compressive stress at the saturation point of the spring material.
Intermediate layer 128 is formed with an internal stress that is between the isotropic compressive internal stress of layer 126 and the tensile internal stress of layer 127 to reduce the stress gradient between compressive layer 126A and tensile layer 127A.
Stress saturation causes the spring material to become essentially isotropic (uniform) because further applied stress pushes the spring material beyond its yield point, producing relaxation of the material that relieves the additional stress and causes the internal stress to remain at the saturated level.
www.patentstorm.us /patents/6866255.html   (12179 words)

 CMACN Chronicles - Summer 1997   (Site not responding. Last check: 2007-10-29)
Using the unconfined masonry stress strain curve in Figure 3, i.e., the curve OAB, it is clear that the maximum stress occurs at a strain of 0.002.
Therefore, Figure 5(b) shows how the compressive stress varies in the masonry between the wall cross-section locations A and C. The total compressive force from the masonry is obtained by adding the forces from the three compressive forces shown in Figure 5(b).
The maximum stress still is assumed to occur at point A in Figure 3 where the strain is 0.002, but the distance from the neutral axis to location B in Figure 5(a) decreases from (2c/3) to (c/3).
www.cmacn.org /publications/chronicles/summer97   (2223 words)

 Arc tube having compressive stress and method for manufacture of an arc tube - Patent 6903510
For this reason, the compressive stress and the tensile stress are alternately generated on the arc tube body by repeatedly turning on and off the arc tube.
10, the stress remains along the junction surface of the molybdenum foil 30 and the arc tube body 20 which are pinch sealed on both sides of the junction surface by a pressure applied to the portion 20B′ to be pinch sealed during the pinch seal.
The magnitude of the residual compressive stress is determined by the spacing D(B) between the step-up plane portions 2a2 of the front surface portions 2a which is obtained with the abutment of the stopper portions 2c and the stopper receiving portions 2d in the pinchers 2.
www.freepatentsonline.com /6903510.html   (4171 words)

 Lecture 4
Theta- angle formed by an inclined plane with the maximum and minimum compressive stress directions, and measured from the minimum stress position.
Principle Stresses sigma 1 (maximum compressive stress) and sigma 3 (minimum compressive stress) plot as two points on the horizontal axis.
relative sense of shear and orientation of principal stress axes
www.uwsp.edu /geo/faculty/hefferan/Geol320/mohrsstress.htm   (487 words)

 glossary of materials testing terms: c
Compressive stress and strain are calculated and plotted as a stress-strain diagram which is used to determine elastic limit, proportional limit, yield point, yield strength and (for some materials) compressive strength.
Compressive strength is calculated by dividing the maximum load by the original cross-sectional area of a specimen in a compression test.
To determine stress relaxation of material, specimen is deformed a given amount and decrease in stress over prolonged period of exposure at constant temperature is recorded.
www.instron.com /wa/applications/glossary/c.aspx   (918 words)

 AllRefer.com - strength of materials (Physics) - Encyclopedia
Stress is the internal force exerted by one part of an elastic body upon the adjoining part, and strain is the deformation or change in dimension occasioned by stress.
When a body is subjected to pull, it is said to be under tension, or tensional stress, and when it is being pushed, i.e., is supporting a weight, it is under compression, or compressive stress.
According to Hooke's law, the stress created in an elastic material is proportional to strain, within the elastic limit (see elasticity).
reference.allrefer.com /encyclopedia/S/strength.html   (467 words)

 Tensile Fracturing of Stiff Rock Layers under Triaxial Compressive Stress State   (Site not responding. Last check: 2007-10-29)
Eshelby’s inclusion analysis is used to show that regional compressive stresses, which are associated with overburden and tectonic loading, could generate tensile stresses of high magnitude within the limestone layers.
The stress amplification within a stiff inclusion is defined here by the ratio between a stress component in the inclusion and the corresponding stress component in the medium.
As the stiffness ratio depends on the lithology of the limestone layers, the amplified stresses would prevail as long as the tectonic stresses are active, leading to continuation of the fracturing and to the observed high fracture density.
earth.es.huji.ac.il /reches/Publications/cancun   (2486 words)

 Compressive Stress
Because tensile and compressive loads produce stresses that act across a plane, in a direction perpendicular (normal) to the plane, tensile and compressive stresses are called normal stresses.
The shear stress is equal to the force divided by the area of the face parallel to the direction in which the force acts, as shown in Figure 1(c).
Compressive stress is applied from the outside at other locations on the wall due to outside pressure, temperature, and constriction of the supports associated with the vessel.
www.tpub.com /doematerialsci/materialscience16.htm   (456 words)

 Compressive stress
Compressive stress is the stress applied to materials resulting in their compaction (decrease of volume).
When a material is subjected to compressive stress then this material is under compression.
Compressive stress has stress units (force per unit area), usually with negative values to indicate the compaction.
www.dejavu.org /cgi-bin/get.cgi?ver=93&url=http://articles.gourt.com/%22http%3A%2F%2Farticles.gourt.com%2F%3Farticle%3Dcompressive   (240 words)

 The Effect of Local Halo Pin Care Reagents on Cranial Radial Compressive Stress (When Tightening Halo Pins) - Journal ...
The last variable to be determined in the calculations of radial compressive stress is the pin's area of contact as a function of applied torque and thread friction (reagent) As the halo pin is tightened, the skull is penetrated proportionately deeper (see Figure 2).
Polynomial regression was used to determine the relationship between radial compressive stress and torque for each of the coating reagents and the uncoated condition.
Radial compressive force variations were relatively small for the low-friction reagents (2.3 to 7.85 N), com pared to that of the high-friction reagents (6.4 to 13 N) (see Table B).
www.oandp.org /jpo/library/1993_03_067.asp   (2474 words)

 Method for forming low compressive stress fluorinated ozone/TEOS oxide film - US Patent 6121164   (Site not responding. Last check: 2007-10-29)
Specifically, high tensile stress in the film causes the substrate to bend in a concave manner, while high compressive stress in the film causes the substrate to bend in a convex manner.
It is optimal that IMD layers have a low compressive stress, avoiding concave or convex bending of the substrate, in order to avoid hillocking of metal during subsequent processing steps.
Stress as a function of time was measured to test the stability of the films.
www.patentstorm.us /patents/6121164.html   (8905 words)

 [No title]
Usually the stress distribution is tensile in the core and compressive at the surface.
Since the outer layer has already solidified, the shrinkage of the inner layer is resisted by the solidified outer layer, thus leading to a tensile stress in the outer layer and compressive stress in the inner layer.
Although many effects contribute to the residual stresses during injection molding of polymers, e.g., packing pressure, viscoelastic relaxation, non-constant material properties, degree crystallinity, etc., its formation may be adequately modeled using a one-dimensional thermo-elastic treatment that assumes constant material properties.
www.me.umn.edu /~kstelson/research_sbp/sbp/zhang.html   (1417 words)

 1994-08 Compressive Stress Depths
Inducing a uniform depth of residual compressive stress on a die's surface is a critical step to extending the life of the tool, especially in the case of EDM production methods.
A uniform compressive stress layer on the tool's surface will not allow the propagation of a crack into or through this compressive layer unless the effective yield strength of the steel is exceeded.
As confirmed by this test, the amount and depth of compressive stress at different subsurface levels was found to be directly proportional to the "T" numbers, with the T-10 process having the least amount and T-61 having the most.
www.badgermetal.com /newsletters/1994-08.htm   (679 words)

 5287. Compressive stress 
Can one part which is shotpeeened to make compressive stress in the part counteract macrocracks in chromium deposit if the compressive stress is higher than tension stress in the chromium deposit.
As you probably know, a tiny crack in the surface of a part is a stress concentration point, such that cracks propagate (sometimes to failure) in a part with fatigue loading.
A stress riser is any flaw in the metal that causes an accumulation of stresses in that area.
www.finishing.com /52/87.shtml   (740 words)

 ARCH 461/561 Lecture 23 Compressive Stress Example Problem   (Site not responding. Last check: 2007-10-29)
The stress at the point between the post and the steel bearing plate is dictated by the smallest area being loaded.
The stress between the two is again 6400 pounds divided by 64 square inches for a total stress of 100 psi.
The stress between the plate and the concrete floor is also determined by the smallest area.
darkwing.uoregon.edu /~struct/courseware/461/461_example_problems/ex_prob_lecture_23/461_example23-2.html   (192 words)

 Shear and Stress   (Site not responding. Last check: 2007-10-29)
Stress is defined as the perpendicular force per unit area applied to an object, in a way that compresses (compressive stress) or stretches (tensile stress) the object.
Since E = stress/strain, strain = stress/E. A stress of 3,000 lb on the one square inch pillar yields a strain of.001.
Shear stress, or just shear, is similar to stress, except that the force is applied such that the material is sheared or twisted.
www.uvi.edu /Physics/SCI3xxWeb/Structure/ShearStress.html   (1298 words)

 Micro-scale Residual Stress Manipulation in Shock Assisted Laser Machining
For instance, thermally induced stress in laser drilling and scribing of ceramics was shown in simulation to induce a very thin layer of compressive residual stress at the surface of the hole, while substantial tensile stresses develop over a thick layer below and parallel to the surface (Modest, 1997; Modest and Thomas, 1999).
Numerical analysis of the heat affected zone and residual stress distributions for laser cutting of stainless steel shown that along the cutting edge there are high levels of tensile stress that sharply reverts to compressive stress once away from the edge (Li and Sheng, 1995; Sheng and Joshi, 1995).
J, in-plane (x-y) compressive residual stress is imparted on the surface of copper samples within a region of about two radii of the laser beam, and over 150 MPa compressive stress is imparted 70 microns into the target material.
www.columbia.edu /cu/mechanical/mrl/ntm/images/shock/lsp.htm   (2576 words)

1.1 This test method is used to determine the compressive creep characteristics of drainage geotextiles, geocomposites, geonets, or any other geosynthetic associated with drainage at a constant temperature, when subjected to a constant compressive stress.
A particular geosynthetic may be evaluated at a series of compressive stresses in order to develop a family of design curves.
The loading platen should be attached to the normal stress assembly in such a way that no stress is placed on the specimen until the commencement of the test.
www.drexel.edu /gri/member/GS/GS4/GS4.html   (1265 words)

 Compression springs, extension springs, torsion springs, wire forms, precision springs at Rockford Spring Company, a ...
When a residual compressive stress is produced in the surface, the tensile stress created by the applied load must first overcome the residual compressive stress before the resultant surface stress becomes tensile.
For the part to be in equilibrium, the total area of the region in compression must be equal to the area in tension.
Compressive stress induced in the peened surface of a shotpeened beam (A) prevents tensile stresses from occurring after a bending moment is applied to the part.
www.rockfordspring.com /shotpeen.asp   (570 words)

 Effect of confinement induced compressive stress on the ballistic performance of ceramic armor
Inducing residual compressive stresses by confinement can delay the onset of tensile failure and provide confinement of ceramic particles after failure.
The goal with the present study is to induce a compressive preload of 30 Ksi in ceramic tiles, with the purpose of improving ballistic properties of ceramic materials, by means of thermal expansion and phase transformation.
Future work includes stress evaluation in confined tiles; both by thermal and phase transformation means, and a comparison of the two concepts must be made based on achieved stress levels, feasibility and economical aspects.
epubl.luth.se /1402-1617/2001/251/index.html   (427 words)

 Metal forming glossary - C - from Advantage Fabricated Metals
A closed-die squeezing operation in which all surfaces of a workpiece are confined or restrained, resulting in a well-defined imprint of the die on the work.
The maximum compressive stress a material is capable of developing.
In the case of ductile, malleable, or semi-viscous materials (which do not fail in compression by a shattering fracture), the value obtained for compressive strength is an arbitrary value dependent on the degree of distortion that is regarded as effective failure of the material.
www.advantagefabricatedmetals.com /metalformingglossaryc.html   (2934 words)

 Transverse Compressive Stress-Strain Behavior of Thick Kevlar/Epoxy Laminates
The room-temperature compressive stress-strain response of quasi-isotropic Kevlar 49 fabric/epoxy composites was studied.
Increasing the porosity from 1 to 20% caused (a) the initial modulus to decrease from 6.0 to 1.4 GPa, (b) the strength to reduce from 1150 to 580 MPa, (c) Poisson's ratio to change from 0.15 to 0.06, and (d) the failure strain to increase from 16 to 26%.
Computed maximum shear stresses along 45-deg planes were of the same magnitude as measured strengths from shear tests using samples oriented to produce shear across layers of fabric.
www.astm.org /DIGITAL_LIBRARY/STP/PAGES/STP36206S.htm   (354 words)

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